KR20230079531A - Ultraviolet curable adhesive composition, adhesive film comprising same, polarizing film comprising same and display device comprising polarizing film - Google Patents

Abstract

The present application relates to an ultraviolet (UV) curable adhesive composition, an adhesive film comprising the same, a polarizing film comprising the same, and a display device comprising the polarizing film. The UV curable adhesive composition comprises: a first epoxy resin which has two or more epoxy groups in a molecule, wherein at least one of the epoxy groups is an alicyclic epoxy group; a second epoxy resin which has two or more epoxy groups in a molecule, wherein the epoxy groups are non-alicyclic epoxy groups; multifunctional acrylates; a photoinitiator; and a photosensitizer.

Description

A UV curing adhesive composition, an adhesive film containing the same, a polarizing film containing the same, and a display device including the polarizing film

The present application relates to a UV curing adhesive composition, an adhesive film including the same, a polarizing film including the same, and a display device including the polarizing film.

Recently, with the development of optical technology as a stepping stone, various types of displays such as plasma display panel (PDP), liquid crystal display (LCD), and organic light emitting diodes (OLED), which replace conventional cathode ray tubes, are being developed. Display devices using the method are proposed and marketed. Recently, the characteristics required for these display devices are becoming more sophisticated, and accordingly, the characteristics required for peripheral components such as optical films and polarizing films applied to the display devices are also becoming more sophisticated.

Liquid crystal displays are used in various display devices such as TVs, mobile phones, car navigation systems, portable game devices, and other portable terminals by taking advantage of features such as low power consumption, low voltage operation, light weight, and thinness. Examples of these liquid crystal display devices include VA (Vertical Alignment) mode, IPS (In-Plane Switching) mode, FFS (Fringe Field Switching) mode, and OCB (Optical Compensated Bend) mode. These liquid crystal displays are generally composed of a backlight, a liquid crystal cell containing liquid crystal molecules sandwiched between two electrodes, and two polarizing plates provided on both sides of the liquid crystal cell, and when a voltage is applied, the change in the optical refractive index of the liquid crystal molecules Transmitted light can be controlled and an image can be displayed. Also, in these modes, the light absorption axes of the two polarizing films are arranged at 90° to each other so that light does not transmit when no voltage is applied to the liquid crystal cell (when no voltage is applied). A liquid crystal display device that displays black when a low voltage is applied and displays white when a voltage is applied is called a normal black type.

Recently, in the polarizer market, efforts have been made to minimize defects and increase product productivity. In the past, TAC (Triacetyl cellulose), a moisture-permeable substrate (WVRT>150g/m ² /24h), has been used as a protective material for polarizers, and polarizers have been manufactured with water-based adhesives. Since a substrate (WVRT<150g/m ² /24h) is mainly used, a UV curable adhesive is mainly used instead of a conventional water-based adhesive.

When using the existing moisture-permeable protective substrate, it was possible to attach the upper and lower protective substrates of the polarizer with one type of adhesive. There is a problem that it is difficult to implement sufficient adhesive strength as a water-based adhesive to use only the adhesive.

That is, an adhesive composition that has good adhesion to a moisture-permeable protective substrate has disadvantageous adhesion to a moisture-impermeable substrate, and an adhesive composition that has good adhesion to a moisture-impermeable protective substrate has disadvantageous adhesion to a moisture-permeable substrate.

In order to solve this problem, it is common to use an adhesive applied to the current polarizing plate separately for the upper and lower surfaces according to the moisture-permeable and non-moisture-permeable substrates. However, if the adhesive is used separately for the moisture-permeable substrate and the non-moisture-permeable substrate, there is an advantage that the adhesive strength is improved, but the adhesive must be replaced every time depending on the product group, and the cost increases and the productivity of the product decreases due to the replacement of the adhesive. is happening

When the adhesive applied to the polarizing film is replaced once, immobility generally occurs for about 2 to 6 hours, and additional costs such as path change due to wet/dry change, adhesive discharge/filling, mesh roll replacement, pipe cleaning/washing, etc. time happens

Therefore, it is necessary to develop an adhesive layer applied to a polarizing plate that can be used regardless of the type of protective substrate (moisture-permeable substrate and non-moisture-permeable substrate) attached to the polarizing plate according to the currently applied product group.

Japanese Registered Patent Publication 6536022

The present application relates to a UV curing adhesive composition, an adhesive film including the same, a polarizing film including the same, and a display device including the polarizing film.

An exemplary embodiment of the present specification includes a first epoxy resin having two or more epoxy groups in a molecule and at least one of the epoxy groups being an alicyclic epoxy group; a second epoxy resin having two or more epoxy groups in a molecule, wherein the epoxy group is a non-alicyclic epoxy group; polyfunctional acrylate; photoinitiators; and a photosensitizer, wherein the second epoxy resin comprises an epoxy compound (A) containing an alicyclic group in a molecule and an epoxy compound (B) containing an alicyclic group in a molecule, wherein the Based on 100 parts by weight of the second epoxy resin, 55 parts by weight or more and 95 parts by weight or less of the epoxy compound (A) containing the alicyclic group in the molecule and 5 parts by weight or more of the epoxy compound (B) containing the alicyclic group in the molecule 45 parts by weight or more It provides a UV curable adhesive composition comprising the following parts.

In another exemplary embodiment, an adhesive film including a UV curable adhesive composition or a cured product thereof according to the present application is provided.

In another exemplary embodiment, a polarizer; A first adhesive layer and a second adhesive layer provided on both sides of the polarizer; a transparent protective film having a moisture permeability of 150 g/m ² /24h or less provided on a surface opposite to the surface of the first adhesive layer in contact with the polarizer; And a transparent protective film having a water vapor transmission rate of 150 g/m ² /24h or more provided on a surface opposite to the surface of the second adhesive layer in contact with the polarizer, wherein the first adhesive layer and the second adhesive layer are Provided is a polarizing film that is an adhesive film according to the present application.

Finally, a display device including the polarizing film according to the present application is provided.

A UV curable adhesive composition according to an exemplary embodiment of the present invention includes a first epoxy resin having two or more epoxy groups in a molecule, and at least one of the epoxy groups being an alicyclic epoxy group; a second epoxy resin having two or more epoxy groups in a molecule, wherein the epoxy group is a non-alicyclic epoxy group; polyfunctional acrylate; photoinitiators; and a photosensitizer. In particular, the second epoxy resin includes an epoxy compound (A) containing an alicyclic group in a molecule and an epoxy compound (B) containing an alicyclic group in a molecule, based on 100 parts by weight of the second epoxy resin. 55 parts by weight or more and 95 parts by weight or less of the epoxy compound (A) containing an alicyclic group and 5 parts by weight or more and 45 parts by weight or less of the epoxy compound (B) containing an alicyclic group in the molecule, and moisture permeability to be bonded Or it has a characteristic of exhibiting excellent adhesive strength regardless of the non-moisture permeable substrate.

In addition, the UV curable adhesive composition according to an exemplary embodiment of the present invention includes a specific content of polyfunctional acrylate and lowers the surface energy of the adhesive layer containing the same, thereby preventing air bubbles during the process and applying properties to a polarizing plate or substrate. (Wetting property) is excellent, and the appearance quality of the polarizing film including the same is excellent.

1 is a diagram showing a laminated structure of a polarizing film according to an exemplary embodiment of the present specification.

Before describing the present invention, some terms are first defined.

In the present specification, when a part "includes" a certain component, it means that it may further include other components, not excluding other components unless otherwise stated.

In the present specification, 'p to q' means a range of 'p or more and q or less'.

In the present specification, acrylate means to include both acrylate and (meth)acrylate.

In the present specification, the meaning that a polymer includes a certain monomer as a monomer unit means that the monomer participates in a polymerization reaction and is included as a repeating unit in the polymer. In the present specification, when a polymer includes a monomer, this is interpreted as the same as that the polymer includes a monomer as a monomer unit.

In the present specification, it is understood that the term 'polymer' is used in a broad sense including a copolymer unless otherwise specified as 'a homopolymer'.

In the present specification, "monomer unit" means a state in which the compound is polymerized and bonded to the polymer.

In the present specification, the weight average molecular weight (Mw) and the number average molecular weight (Mn) are measured using a commercially available monodisperse polystyrene polymer (standard sample) of various degrees of polymerization for molecular weight measurement as a standard material, and gel permeation chromatography (Gel Permeation It is the molecular weight in terms of polystyrene measured by chromatography; GPC). In this specification, molecular weight means a weight average molecular weight unless otherwise specified.

Hereinafter, it will be described in detail with reference to the drawings so that those skilled in the art can easily practice the present invention. However, the present invention may be embodied in many different forms and is not limited to the description below.

An exemplary embodiment of the present specification includes a first epoxy resin having two or more epoxy groups in a molecule and at least one of the epoxy groups being an alicyclic epoxy group; a second epoxy resin having two or more epoxy groups in a molecule, wherein the epoxy group is a non-alicyclic epoxy group; polyfunctional acrylate; photoinitiators; and a photosensitizer, wherein the second epoxy resin comprises an epoxy compound (A) containing an alicyclic group in a molecule and an epoxy compound (B) containing an alicyclic group in a molecule, wherein the Based on 100 parts by weight of the second epoxy resin, 55 parts by weight or more and 95 parts by weight or less of the epoxy compound (A) containing the alicyclic group in the molecule and 5 parts by weight or more of the epoxy compound (B) containing the alicyclic group in the molecule 45 parts by weight or more It provides a UV curable adhesive composition comprising the following parts.

The UV curable adhesive composition according to an exemplary embodiment of the present invention has the above composition and content range in the adhesive composition, and exhibits excellent adhesive strength regardless of a moisture-permeable or non-moisture-permeable substrate to be bonded.

Each feature of the adhesive composition included in the present application is described below.

In one embodiment of the present application, the UV curable adhesive composition includes a first epoxy resin having two or more epoxy groups in a molecule, and at least one of the epoxy groups is an alicyclic epoxy group.

The first epoxy resin may have 2 or more epoxy groups in a molecule, specifically, 2 or more and 5 or less epoxy groups, and more specifically, 2 or more and 4 or less epoxy groups, or two epoxy groups.

In an exemplary embodiment of the present application, at least one of the epoxy groups of the first epoxy resin may have an alicyclic epoxy group.

In an exemplary embodiment of the present application, an alicyclic epoxy group may mean that a substituent to which the epoxy group is bonded has an alicyclic.

In one embodiment of the present application, the first epoxy resin may have two epoxy groups in a molecule, and the two epoxy groups may have an alicyclic epoxy group.

That is, in an exemplary embodiment of the present application, the first epoxy resin may have the following structure, but is not limited thereto.

In one embodiment of the present application, based on 100 parts by weight of the UV curable adhesive composition, the first epoxy resin is 10 parts by weight or more and 50 parts by weight or less, and the second epoxy resin is 25 parts by weight or more and 50 parts by weight or less. A UV curable adhesive composition is provided.

In another embodiment, based on 100 parts by weight of the UV curable adhesive composition, the first epoxy resin is 10 parts by weight or more and 50 parts by weight or less, preferably 10 parts by weight or more and 45 parts by weight or less, more preferably 20 parts by weight It may include more than 40 parts by weight or less, specifically 35 parts by weight or more and 40 parts by weight or less.

As the composition and content of the first epoxy group are satisfied, it has a rigid structure, has a high Tg value, can serve as an overall skeleton, has excellent mechanical properties and can rapidly control the curing rate.

In one embodiment of the present application, the UV adhesive composition has two or more epoxy groups in a molecule, and the epoxy group includes a second epoxy resin that is a non-cycloaliphatic epoxy group.

The second epoxy resin may have 2 or more epoxy groups in a molecule, specifically, 2 or more and 5 or less epoxy groups, and more specifically, 2 or more and 4 or less epoxy groups, or two epoxy groups.

In one embodiment of the present application, the epoxy group of the second epoxy resin may have a non-cycloaliphatic epoxy group.

In an exemplary embodiment of the present application, a non-alicyclic epoxy group may mean that a substituent to which the epoxy group is bonded has a non-alicyclic group.

That is, in an exemplary embodiment of the present application, the second epoxy resin may have the following structure, but is not limited thereto.

In one embodiment of the present application, the second epoxy resin may include an epoxy compound (A) containing an alicyclic group in a molecule and an epoxy compound (B) containing an alicyclic group in a molecule.

In one embodiment of the present application, in the epoxy compound (A) containing an alicyclic group in the molecule, the substituent to which the epoxy group is bonded is non-alicyclic, but the molecule containing the epoxy compound (A) itself contains an alicyclic group. can mean

In one embodiment of the present application, in the epoxy compound (B) containing an alicyclic group in the molecule, the substituent to which the epoxy group is bonded is non-alicyclic, and the molecule itself including the epoxy compound (B) contains the non-alicyclic group. can mean doing

In an exemplary embodiment of the present application, the epoxy compound (A) containing an alicyclic group in a molecule is represented by Formula 1 below, and the epoxy compound (B) containing an alicyclic group in a molecule is represented by Formula 2 below It provides a UV curable adhesive composition that will be.

[Formula 1]

[Formula 2]

In Formula 1 and Formula 2,

m is an integer from 1 to 6;

n is an integer from 1 to 10;

In an exemplary embodiment of the present application, m may be an integer of 1 to 6, may be an integer of 1 to 5, may be an integer of 2 to 4, and preferably may be an integer of 4.

In one embodiment of the present application, n may be an integer of 1 to 10, may be an integer of 1 to 8, may be an integer of 2 to 6, preferably an integer of 4.

In an exemplary embodiment of the present application, based on 100 parts by weight of the second epoxy resin, 55 parts by weight or more and 95 parts by weight or less of the epoxy compound (A) containing the alicyclic group in the molecule and the epoxy containing the alicyclic group in the molecule It provides a UV curing adhesive composition comprising 5 parts by weight or more and 45 parts by weight or less of compound (B).

In another exemplary embodiment, based on 100 parts by weight of the second epoxy resin, 55 parts by weight or more and 95 parts by weight or less of the epoxy compound (A) containing an alicyclic group in the molecule; It may include preferably 55 parts by weight or more and 90 parts by weight or less, more preferably 60 parts by weight or more and 80 parts by weight or less.

In another embodiment, based on 100 parts by weight of the second epoxy resin, 5 parts by weight or more and 45 parts by weight or less of the epoxy compound (B) containing an alicyclic group in the molecule; Preferably, it may include 10 parts by weight or more and 40 parts by weight or less, more preferably 20 parts by weight or more and 40 parts by weight or less.

In the adhesive composition according to the present application, the second epoxy group is composed of the epoxy compound (A) and the epoxy compound (B), and includes the weight part as described above, in particular, the content of the epoxy compound (A) is the epoxy compound ( It is higher than the content of B), so that it has excellent adhesive strength regardless of the wetting property of the adhesive containing it later and the moisture-permeable / non-moisture-permeable substrate.

In particular, the adhesive composition according to the present application includes a specific epoxy compound (A) in the above range, has excellent adhesive strength with a polyvinyl alcohol-based polarizer, and has a rigid ring in the structure, so that it is more than a structure consisting only of a linear structure. The adhesive layer can be made relatively rigid. In addition, it is hydrophobic due to a rigid ring, which can suppress water permeation, and has excellent adhesion to non-moisture permeable substrates.

In one embodiment of the present application, the multifunctional acrylate means an acrylate having two or more functional groups in a molecule, and the functional group may be an acrylate group.

In one embodiment of the present application, the number of functional groups of the multifunctional acrylate may be 2 or more and 10 or less, preferably 2 or more and 6 or less, more preferably 2 or more and 5 or less.

When the multifunctional acrylate has two functional groups, it can be differently expressed as bifunctional acrylate, and when it has three functional groups, it can be differently expressed as trifunctional acrylate.

In an exemplary embodiment of the present application, representative examples of bifunctional acrylates include alkylene glycol di(meth)acrylates, polyoxyalkylene glycol di(meth)acrylates, and halogen-substituted alkylene glycol di(meta) Acrylates, di(meth)acrylates of aliphatic polyols, di(meth)acrylates of hydrogenated dicyclopentadiene or tricyclodecane dialkanol, di(meth)acrylates of dioxane glycol or dioxane dialkanol di(meth)acrylates of alkylene oxide adducts of bisphenol A or bisphenol F, and epoxy di(meth)acrylates of bisphenol A or bisphenol F.

In one embodiment of the present application, more specific examples of the bifunctional acrylate, ethylene glycol di (meth) acrylate, 1,3-butanediol (meth) acrylate, 1,4-butanediol (meth) acrylate , 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, neopentylglycol di(meth)acrylate, trimethylolpropanedi(meth)acrylate, pentaerythritol Di(meth)acrylate, ditrimethylolpropane di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene Glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, polytetramethylene glycol di (meth) acrylate, hydroxypivaric acid neopentyl glycol ester Di(meth)acrylate, 2,2-bis[4-{2-(2-(meth)acryloyloxyethoxy)ethoxy}phenyl]propane, 2,2-bis[4-{2-( 2-(meta)acryloyloxyethoxy)ethoxy}cyclohexyl]propane, hydrogenated dicyclopentadienyl di(meta)acrylate, tricyclodecanedimethanol di(meth)acrylate, 1,3-di Dioxane-2,5-diyl di(meth)acrylate [alias: dioxane glycol di(meta)acrylate], acetal compound of hydroxypivalaldehyde and trimethylolpropane [chemical name: 2-(2-hydroxy -1,1-dimethylethyl) -5-ethyl-5-hydroxymethyl-1,3-dioxane] di (meth) acrylate, 1,3,5-tris (2-hydroxyethyl) isoxy di(meth)acrylates of anurates; and the like.

In one embodiment of the present application, a representative example of the tri- or higher-functional polyfunctional acrylate is poly(meth)acrylate of a tri- or higher-valent aliphatic polyol. Specific examples thereof include glycerin tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tri(meth)acrylate, ditrimethylolpropanetetra(meth)acrylate, and pentaerythritol. Tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, Glycerin ethylene oxide-modified tri(meth)acrylate, ethylene oxide-modified trimethylolpropane tri(meth)acrylate, and the like.

Meanwhile, acrylate oligomers include urethane (meth)acrylate oligomers, polyester (meth)acrylate oligomers, epoxy (meth)acrylate oligomers, and the like.

In one embodiment of the present application, the multifunctional acrylate is hydroxypivalic acid neopentyl glycol diacrylate (HYDROXYPIVALIC ACID NEOPENTYLGLYCOL DIACRYLATE); Or it may be tris (2-hydroxy ethyl) isocyanurate triacrylate.

In one embodiment of the present application, one type of the multifunctional acrylate may be used.

In one embodiment of the present application, two types of the multifunctional acrylate may be used.

In one embodiment of the present application, the UV curing adhesive composition includes 10 parts by weight or more and 60 parts by weight or less of the multifunctional acrylate based on 100 parts by weight of the UV curing adhesive composition, and the functional group of the multifunctional acrylate is an acrylate group. An adhesive composition is provided.

In another embodiment, based on 100 parts by weight of the UV curable adhesive composition, the polyfunctional acrylate is 10 parts by weight or more and 60 parts by weight or less, preferably 10 parts by weight or more and 55 parts by weight or less, more preferably 15 parts by weight More than 50 parts by weight or less, specifically, 20 parts by weight or more and 30 parts by weight or less may be satisfied.

As described above, as the multifunctional acrylate is included in the above range in the UV curing adhesive composition, the spreadability of the substrate is excellent in the adhesive composition later, showing excellent properties during adhesive application and also providing a moisture-permeable substrate or non-moisture permeable substrate on both sides of the polarizing plate. Even when substrates are laminated, it has a characteristic capable of exhibiting excellent adhesive strength.

In one embodiment of the present application, the UV curing adhesive composition includes a photoinitiator; and a photosensitizer.

In this application, the photoinitiator may be any conventionally known photoinitiator capable of initiating polymerization of a polymerizable monomer and a polymerizable multifunctional acrylate by irradiation of ultraviolet rays. The photoinitiator may include a cationic initiator, and specific examples of the photoradical polymerization initiator include acetophenone, 3-methylacetophenone, benzyldimethylketal, 1-(4-isopropyl phenyl)-2-hydroxy-2 -methylpropan-1-one,2-methyl-1-[4-(methylthio)phenyl-2-morpholino propan-1-one and 2-hydroxy-2-methyl-1-phenylpropan-1- acetophenone-based initiators such as one; benzophenone-based initiators such as benzophenone, 4-chlorobenzophenone and 4,4'-diaminobenzophenone; benzoin ether-based initiators such as benzoin propyl ether and benzoin ethyl ether; Thioxanthone-based initiators such as 4-isopropylthioxanthone; Others include xanthone, fluorenone, camphor quinone, benzaldehyde, and anthraquinone.

In an exemplary embodiment of the present application, the photoinitiator is a compound that generates a cationic species or a Lewis acid by irradiation of active energy rays such as ultraviolet rays, and refers to a compound that initiates a cationic polymerization reaction by acting on a cationic polymerizable group such as an epoxy group. .

In one embodiment of the present application, the photoinitiator may include a sulfonium salt or an iodonium salt.

According to an exemplary embodiment of the present specification, the photoinitiator is a triazine-based compound, a biimidazole compound, an acetophenone-based compound, an O-acyloxime-based compound, a thioxanthone-based compound, a phosphine oxide-based compound, a coumarin-based compound and benzophenone It may be substituted with one or two or more substituents selected from the group consisting of paddy-based compounds.

Specifically, according to an exemplary embodiment of the present specification, the photoinitiator is 2,4-trichloromethyl-(4'-methoxyphenyl)-6-triazine, 2,4-trichloromethyl-(4'-methoxyphenyl) Toxystyryl) -6-triazine, 2,4-trichloromethyl- (fiplonil) -6-triazine, 2,4-trichloromethyl- (3', 4'-dimethoxyphenyl) -6 -triazine, 3-{4-[2,4-bis(trichloromethyl)-s-triazin-6-yl]phenylthio}propanoic acid, 2,4-trichloromethyl-(4'-ethyl ratio) triazine compounds such as phenyl)-6-triazine or 2,4-trichloromethyl-(4'-methylbiphenyl)-6-triazine; 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenyl biimidazole or 2,2'-bis(2,3-dichlorophenyl)-4,4',5 Biimidazole compounds, such as 5'-tetraphenyl biimidazole; 2-Hydroxy-2-methyl-1-phenylpropan-1-one, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 4-(2-hydroxyethene Toxy)-phenyl (2-hydroxy)propyl ketone, 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-2-phenyl acetophenone, 2-methyl-(4-methylthiophenyl)-2-mol Acetopes such as polyno-1-propan-1-one (Irgacure-907) or 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one (Irgacure-369) paddy field compound; O-acyloxime compounds such as Ciba Geigy's Irgacure OXE 01 and Irgacure OXE 02; benzophenone compounds such as 4,4'-bis(dimethylamino)benzophenone or 4,4'-bis(diethylamino)benzophenone; thioxanthone-based compounds such as 2,4-diethyl thioxanthone, 2-chloro thioxanthone, isopropyl thioxanthone, or diisopropyl thioxanthone; 2,4,6-trimethylbenzoyl diphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentyl phosphine oxide or bis(2,6-dichlorobenzoyl) propyl phosphine oxide phosphine oxide compounds such as the like; 3,3'-carbonylvinyl-7-(diethylamino)coumarin, 3-(2-benzothiazolyl)-7-(diethylamino)coumarin, 3-benzoyl-7-(diethylamino)coumarin, 3-benzoyl-7-methoxy-coumarin or 10,10'-carbonylbis[1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H,11H-Cl] A coumarin-based compound such as -benzopyrano[6,7,8-ij]-quinolizin-11-one may be used alone or in combination of two or more, but is not limited thereto.

In an exemplary embodiment of the present application, the photoinitiator is to promote polymerization to improve the curing rate, and as the photoinitiator, cationic initiators commonly used in the art may be used without limitation.

In addition, in one embodiment of the present application, the reactivity of radical polymerization is improved by blending the photosensitizer, and the mechanical strength or adhesiveness of the adhesive layer can be improved. The photosensitizer may be a compound having maximum absorption at a wavelength longer than 380 nm, and examples thereof include carbonyl compounds, organic sulfur compounds, persulfides, redox compounds, azo and diazo compounds, halogen compounds, anthracene compounds, light A reducing dye etc. are mentioned.

In one embodiment of the present application, based on 100 parts by weight of the UV curing adhesive composition, 0.1 part by weight or more and 5 parts by weight or less of the photoinitiator, and 0.1 part by weight or more and 5 parts by weight or less of the photosensitizer are included. A curing adhesive composition is provided.

In another embodiment, based on 100 parts by weight of the UV curable adhesive composition, the photoinitiator is 0.1 parts by weight or more and 5 parts by weight or less, preferably 1 part by weight or more and 4 parts by weight or less, more preferably 1.5 parts by weight or more and 3.5 parts by weight. May include the following.

In another embodiment, based on 100 parts by weight of the UV curing adhesive composition, the photosensitizer is 0.1 parts by weight or more and 5 parts by weight or less, preferably 1 part by weight or more and 3 parts by weight or less, more preferably 1.5 parts by weight or more 2.5 parts by weight or less. parts by weight or less.

In one embodiment of the present application, the UV curing adhesive composition may further include one or more selected from the group consisting of a solvent, a dispersant, a thermal initiator, a crosslinking agent, and a tackifier.

According to an exemplary embodiment of the present specification, the crosslinking agent is hexanedioldi(meth)acrylate, ethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate having 2 to 14 ethylene groups, and trimethylolpropane. Di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, 2-trisacryloyloxymethylethylphthalic acid, the number of propylene groups 2 to 14 propylene glycol di(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, acidic variants of dipentaerythritol penta(meth)acrylate and dipentaerythritol Compounds obtained by esterifying polyhydric alcohols such as mixtures of hexa(meth)acrylates (trade names: TO-2348 and TO-2349 manufactured by Toga Synthetic Co., Ltd., Japan) with α,β-unsaturated carboxylic acids; compounds obtained by adding (meth)acrylic acid to compounds containing a glycidyl group, such as trimethylolpropane triglycidyl ether acrylic acid adducts and bisphenol A diglycidyl ether acrylic acid adducts; Ester compounds of polyhydric carboxylic acids with compounds having hydroxyl groups or ethylenically unsaturated bonds, such as phthalic acid diesters of β-hydroxyethyl (meth)acrylate and toluene diisocyanate adducts of β-hydroxyethyl (meth)acrylates , or adducts with polyisocyanates; (meth)acrylic acid alkyl esters such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate; And 9,9'-bis [4- (2-acryloyloxyethoxy) phenyl] may include one or more selected from the group consisting of fluorene, but is not limited to these, known in the art Common ones can be used.

In addition, the dispersant, thermal initiator, and tackifier may use those known in the art.

Although toluene may be used as the solvent, it is not limited thereto as long as it can dissolve a specific substance, and a general organic solvent may be used accordingly.

An adhesive film comprising a UV curable adhesive composition or a cured product thereof according to the present application is provided.

The adhesive film may be laminated on the base film during manufacture.

In an exemplary embodiment of the present application, the adhesive film may include the adhesive composition according to an exemplary embodiment of the present application as it is.

In an exemplary embodiment of the present application, the adhesive sheet may include a cured product of an adhesive composition according to an exemplary embodiment of the present application.

In one embodiment of the present application, the base film is PET (polyethylene terephthalate), polyester (polyester), PC (polycarbonate), PI (polyimide), PEN (polyethylene naphthalate), PEEK (polyether ether ketone), PAR ( polyarylate), polycylicolefin (PCO), polynorbornene, polyethersulphone (PES), and cycloolefin polymer (COP).

In another exemplary embodiment, the base film may be polyethylene terephthalate (PET).

In one embodiment of the present application, the thickness of the base film is 10 μm or more and 200 μm or less, preferably 15 μm or more and 100 μm or less, more preferably 20 μm or more and 75 μm or less.

Also, the base film is preferably transparent. The meaning here that the base film is transparent indicates that the light transmittance of visible light (400 to 700 nm) is 80% or more.

In one embodiment of the present application, an adhesive film further comprising a release film on one side or both sides of the adhesive film is provided.

The release film may be a hydrophobic film, and is a layer for protecting an adhesive film having a very thin thickness, and refers to a transparent layer attached to one surface of the adhesive film, and a film having excellent mechanical strength, thermal stability, moisture barrier property, isotropy, etc. can be used For example, acetate-based, polyester-based, polyethersulfone-based, polycarbonate-based, polyamide-based, polyimide-based, polyolefin-based, cycloolefin-based, polyurethane-based and acrylic resin films such as triacetyl cellulose (TAC), etc. It can be used, but if it is a commercially available silicon-treated release film, it is not limited thereto.

In one embodiment of the present application, the thickness of the adhesive film is 3 μm or more and 300 μm may be below.

In another exemplary embodiment, the thickness of the adhesive film is 3 μm or more and 100 μm or less, preferably 5 μm or more and 80 μm or less, more preferably 10 μm or more and 50 μm may be below.

When the thickness of the adhesive film is within the above range, rework properties are excellent when erroneously attached, and in particular, no foreign matter is left when the adhesive film is removed.

In one embodiment of the present application, the surface energy of the adhesive film may be 35 mN/m or less.

In one embodiment of the present application, the adhesive film may have a surface water contact angle of 70° or more.

In one embodiment of the present application, the adhesive film may have a surface energy of 35 mN/m or less, a surface energy of 30 N/m or less, a surface energy of 25 mN/m or less, and a surface energy of 5 mN/m or more. there is.

In one embodiment of the present application, the adhesive film may have a surface water contact angle of 70° or more, a surface water contact angle of 100° or more, a surface water contact angle of 110° or more, and a surface water contact angle of 180° or less. can

The adhesive film according to an exemplary embodiment of the present application satisfies the surface number contact angle and surface energy, and satisfies the above range as the UV curing adhesive composition includes monofunctional and multifunctional acrylates of a specific composition and content. It has excellent spreadability with.

In another exemplary embodiment, a polarizer; A first adhesive layer and a second adhesive layer provided on both sides of the polarizer; a transparent protective film having a moisture permeability of 150 g/m ² /24h or less provided on a surface opposite to the surface of the first adhesive layer in contact with the polarizer; And a transparent protective film having a water vapor transmission rate of 150 g/m ² /24h or more provided on a surface opposite to the surface of the second adhesive layer in contact with the polarizer, wherein the first adhesive layer and the second adhesive layer are Provided is a polarizing film that is an adhesive film according to the present application.

At this time, the polarizer is not particularly limited, and a polarizer well known in the art, for example, a film made of polyvinyl alcohol (PVA) containing iodine or a dichroic dye is used.

A polarizer exhibits a characteristic capable of extracting only light vibrating in one direction from incident light vibrating in several directions. These properties can be achieved by stretching poly vinyl alcohol (PVA) with iodine absorption with strong tension. For example, more specifically, the step of swelling the PVA film by soaking it in an aqueous solution, dyeing the swollen PVA film with a dichroic material that imparts polarization, and stretching the dyed PVA film ) to form a polarizer through a stretching step of arranging the dichroic dye material side by side in the stretching direction, and a complementary color step of correcting the color of the PVA film that has passed through the stretching step. However, the polarizing plate of the present invention is not limited thereto.

In one embodiment of the present application, a surface in contact with the polarizer of the first adhesive layer; and an adhesive strength of a surface of the second adhesive layer in contact with the polarizer of 150 gf/inch or more.

In another exemplary embodiment, a surface in contact with the polarizer of the first adhesive layer; and an adhesive strength of a surface of the second adhesive layer in contact with the polarizer of 150 gf/inch or more, preferably 200 gf/inch or more, and 600 gf/inch or less, more preferably 400 gf/inch or less.

That is, in the polarizing film according to the present application, the first protective film is used on the upper part of the polarizer and the second protective film is used on the lower part of the polarizer, and UV curing is performed even when a moisture-permeable substrate is used on the upper part and a moisture-permeable substrate is used on the lower part. The adhesive composition has a certain composition and content, so that the adhesive strength has excellent characteristics as described above.

1 shows a laminated structure of a polarizing film according to an exemplary embodiment of the present application, and specifically, a first adhesive layer 4 and a second adhesive layer 2 are provided on both sides of a polarizer 3, and on top of each It can be seen that the transparent protective film 5 having a moisture vapor transmission rate of 150 g/m ² /24h or less includes the transparent protective film 1 having a moisture vapor transmission rate of 150 g/m ² /24h or more.

Figure 1 is only one example, and the type of protective substrate that can come to the top and bottom of the polarizer is not limited thereto.

In one embodiment of the present application, the first adhesive layer and the second adhesive layer are provided in the same polarizing film.

That is, despite the simultaneous use of a moisture-permeable substrate and a non-moisture-permeable substrate in the polarizer, unlike the conventional method in which several types of adhesives are used, the productivity of the polarizing film is excellent and the adhesive layer is used as the same type of adhesive layer. It has a feature capable of preventing an increase in cost due to replacement.

Finally, a display device including the polarizing film according to the present application is provided.

Hereinafter, the present application will be described in more detail through examples according to the present application and comparative examples not according to the present application, but the scope of the present application is not limited by the examples presented below.

<Example>

Adhesive compositions having the compositions and contents shown in Table 1 below were prepared, respectively.

Thereafter, the UV adhesive composition was applied to both sides of a polarizer (manufactured by Nippon Synthetic Co., Ltd.), and on one side was Fuji's NRT TAC film (water vapor transmission rate>150g/m ² /day) and Toyobo's TA044 PET (water vapor transmission rate <50g/m ² /day) on the opposite side. /day) was laminated and bonded through a roll laminator.

Thereafter, ultraviolet rays were irradiated to the polarizing plate in order to cure the UV adhesive composition. Although the light source of the ultraviolet rays is not particularly limited, a low pressure mercury lamp, an intermediate pressure mercury lamp, a high pressure mercury lamp, an ultra-high pressure mercury lamp, a chemical lamp, a black light lamp, a microwave excited mercury lamp, a metal halide lamp, etc. having a luminescence distribution at a wavelength of 400 nm or less were used.

The polarizer and the protective film for peeling were adhered to each other by curing the adhesive composition for polarizing plate by irradiating ultraviolet rays having a wavelength of 365 nm so that the irradiation amount (integrated light amount) was 2000 mJ/cm ² , and cut into a size of 2 cm in width * 15 cm in length. Thus, a polarizing plate sample was prepared. At this time, the protective film for peeling with respect to each adhesive composition for polarizing plates was subjected to KOH pretreatment if necessary.

The polarizing film is stored at room temperature (20 ° C. or more and 25 ° C. or less. Specifically, 25 ° C.) for 16 hours or more and 30 hours or less immediately after ultraviolet irradiation. Upon completion of curing, a polarizing film was obtained.

First epoxy resin Second Epoxy Resin multifunctional acrylate photoinitiator photosensitizer Celloxide 2021P LD221 LD204 DPGDA Omnicat 250 DETX Example 1 40 15 25 20 3.3 1.7 Example 2 35 15 30 20 3.3 1.7 Example 3 35 15 20 30 3.3 1.7 Comparative Example 1 50 50 - - 3.3 1.7 Comparative Example 2 50 25 25 - 3.3 1.7 Comparative Example 3 40 30 30 - 3.3 1.7 Comparative Example 4 30 15 10 40 3.3 1.7 Comparative Example 5 40 15 - 50 3.3 1.7

In Table 1, it may mean the content part included in the entire adhesive composition (6 types of Table 1). Specifically, in Table 1, parts by weight of each composition are shown based on 100 parts by weight of the total adhesive composition.

In Table 1, Celloxide2021P (Daicel Co.) is (3',4'-epoxycyclohexane)methyl 3,4-epoxycyclohexylcarboxylate, and LD221 (Hajin Chemtech Co.) is 1,4-butanediol diglycylate. LD204 (Hajin Chemtech) is 1,4-cyclohexanedimethanol diglycidyl ether, and Omnicat250 (IGM) is (4-methylphenyl)[4-(2-methylpropyl)phenyl]-hexa Fluorophosphate (1-)in propylene carbonate, and DETX (LAMSON) were used as 2,4-diethylthioxanthone, respectively.

With respect to the polarizing film prepared above, the following Experimental Examples 1 to 4 were evaluated, and the results are shown in Table 2.

Peel force thermal shock resistance curing speed Applicability Protection materials (1) Protection materials (2) -40℃<->80℃ TAC(NRT) PET(TAO44) 100Cycles Example 1 ◎ ◎ O ◎ ◎ Example 2 ◎ ◎ O O ◎ Example 3 ◎ ◎ O ◎ ◎ Comparative Example 1 ◎ X O O O Comparative Example 2 ◎ X O O O Comparative Example 3 ◎ X O O O Comparative Example 4 ◎ O △ ◎ O Comparative Example 5 ◎ O △ ◎ O

<Experimental Example 1: Protective Film Peel Force Test>

The protective film for peeling was peeled at 3 cm or more at a peel speed of 0.5 cm/sec, and the peel force at this time was measured three times to calculate an average value. When measuring the peel force, XT Plus Texture Analyzer (manufactured by TA) was used.

At this time, when the peel force (gf / 20 mm) is 200 gf / 20 mm or more, ◎, 120 gf / 20 mm or more and less than 200 gf / 20 mm, O, 100 gf / 20 mm or more and less than 120 gf / 20 mm.

<Experimental Example 2: Thermal shock evaluation>

The prepared polarizing film was cut to have a length of 150 mm in the direction of the absorption axis and in the direction perpendicular thereto. Thereafter, an adhesive was applied to one side of the peeling protective film, and it was laminated on a glass substrate and left at 25° C. for 24 hours.

Thereafter, the glass substrate was allowed to stand at -40°C for 30 minutes and left at 85°C for 30 minutes 100 cycles were repeated. After applying the thermal shock, it was observed whether a polarizer crack existed from the end of the polarizer in the stretching direction of the polarizer, and when a polarizer crack was observed, the length of the crack was measured. When multiple cracks were observed, it was decided to evaluate using the average value.

It was evaluated as ◎ when no cracks occurred or when the length of the cracks was 2 to 3 mm, 0 when the length of the cracks was around 10 mm, Δ when the length of the cracks was around 50 mm, and X when the cracks occurred in bundles.

<Experimental Example 3: Curing rate>

The adhesive composition for polarizing plates was cured by irradiating ultraviolet light having a wavelength of 365 nm so that the irradiation amount (integrated light amount) was 2000 mJ/cm ² . Immediately after peeling off the protective film, the cured film was rubbed by hand to check whether the film was slipped.

When the curing speed was less than 10 seconds, ◎, more than 10 seconds and less than 20 seconds, O, more than 20 seconds and less than 50 seconds, Δ, more than 50 seconds were evaluated as X.

<Experimental Example 4: Substrate spreadability>

After fixing the protective film (TAC film), the adhesive composition was applied using #3 Bar. Check whether dewetting occurs on the film surface after 30 seconds.

When the substrate had excellent spreadability, it was marked as ◎, when the surface was rough, it was rated as O, and when side shrinkage and circular dewetting occurred, it was evaluated as X.

As can be seen in Table 2, the UV curable adhesive composition according to Examples 1 to 3 of the present invention includes a first epoxy resin having two or more epoxy groups in a molecule, at least one of which is an alicyclic epoxy group; a second epoxy resin having two or more epoxy groups in a molecule, wherein the epoxy group is a non-alicyclic epoxy group; polyfunctional acrylate; photoinitiators; and a photosensitizer. In particular, the second epoxy resin includes an epoxy compound (A) containing an alicyclic group in a molecule and an epoxy compound (B) containing an alicyclic group in a molecule, based on 100 parts by weight of the second epoxy resin. 55 parts by weight or more and 95 parts by weight or less of the epoxy compound (A) containing an alicyclic group and 5 parts by weight or more and 45 parts by weight or less of the epoxy compound (B) containing an alicyclic group in the molecule, and moisture permeability to be bonded Or it could be confirmed that it has a characteristic of exhibiting excellent adhesive strength regardless of the non-moisture permeable substrate.

Comparative Examples 1 to 3 in Table 1 correspond to cases in which polyfunctional acrylate is not included, and based on 100 parts by weight of the second epoxy resin, the epoxy compound (A) containing the alicyclic group in the molecule is not included or It was confirmed that the adhesion to a moisture-permeable or non-moisture-permeable substrate was not good when the same amount as the epoxy compound (B) containing an alicyclic group was included.

In the case of Comparative Examples 4 and 5 of Table 2, all of the UV adhesive compositions of the present invention are included, but the content of the epoxy compound (A) containing an alicyclic group in the molecule is the content of the epoxy compound (B) containing an alicyclic group. To a lesser extent, adhesion to a moisture-permeable or non-moisture-permeable substrate was improved compared to Comparative Examples 1 to 3, but it was confirmed that the thermal shock evaluation and substrate application property were deteriorated.

That is, when synthesizing Examples 1 to 3 and Comparative Examples 1 to 5 of Table 2, the adhesive composition according to the present application has five compositions (first epoxy resin, second epoxy resin, multifunctional acrylate, photoinitiator and It was confirmed that excellent effects were exhibited in the evaluation of peel force/thermal shock resistance/curing speed/substrate application only when the photosensitizer) and content were satisfied.

1: Transparent protective film with a moisture permeability of 150 g/m ² /24 h or more
2: second adhesive layer
3: polarizer
4: first adhesive layer
5: Transparent protective film with a moisture permeability of 150 g/m ² /24h or less

Claims (14)

a first epoxy resin having two or more epoxy groups in a molecule and at least one of the epoxy groups being an alicyclic epoxy group;
a second epoxy resin having two or more epoxy groups in a molecule, wherein the epoxy group is a non-alicyclic epoxy group;
polyfunctional acrylate;
photoinitiators; and
A UV curing adhesive composition containing a photosensitizer,
The second epoxy resin includes an epoxy compound (A) containing an alicyclic group in a molecule and an epoxy compound (B) containing an alicyclic group in a molecule,
Based on 100 parts by weight of the second epoxy resin, 55 parts by weight or more and 95 parts by weight or less of the epoxy compound (A) containing an alicyclic group in the molecule and 5 parts by weight or more of the epoxy compound (B) containing an alicyclic group in the molecule 45 parts by weight or more A UV curable adhesive composition comprising less than one part by weight. The method of claim 1,
Based on 100 parts by weight of the UV curing adhesive composition, the first epoxy resin is 10 parts by weight or more and 50 parts by weight or less, and the second epoxy resin is 25 parts by weight or more and 50 parts by weight or less. The method of claim 1,
The UV curable adhesive composition comprising 0.1 parts by weight or more and 5 parts by weight or less of the photoinitiator based on 100 parts by weight of the UV curable adhesive composition, and including 0.1 parts by weight or more and 5 parts by weight or less of the photosensitizer. The method of claim 1,
Based on 100 parts by weight of the UV curing adhesive composition, 10 parts by weight or more and 60 parts by weight or less of the multifunctional acrylate are included,
The functional group of the multifunctional acrylate is an acrylate group UV curing adhesive composition. The method according to claim 1, wherein the epoxy compound (A) containing an alicyclic group in the molecule is represented by Formula 1 below, and the epoxy compound (B) containing an alicyclic group in the molecule is represented by Formula 2 below. Curing adhesive composition:
[Formula 1]

[Formula 2]

In Formula 1 and Formula 2,
m is an integer from 1 to 6;
n is an integer from 1 to 10; The UV curing adhesive composition according to claim 1, further comprising at least one selected from the group consisting of a solvent, a dispersing agent, a crosslinking agent, a thermal initiator, and a tackifier. An adhesive film comprising the UV curable adhesive composition according to any one of claims 1 to 6 or a cured product thereof. The adhesive film according to claim 7, wherein the adhesive film has a surface energy of 35 mN/m or less and a water contact angle of 70° or more. The method of claim 7,
Adhesive film further comprising a release film on one side or both sides of the adhesive film. The method according to claim 7, wherein the thickness of the adhesive film is 50 ㎛ or more 300 ㎛ An adhesive film of the following. polarizer;
A first adhesive layer and a second adhesive layer provided on both sides of the polarizer;
a transparent protective film having a moisture permeability of 150 g/m ² /24h or less provided on a surface opposite to the surface of the first adhesive layer in contact with the polarizer; and
A polarizing film comprising a transparent protective film having a water vapor transmission rate of 150 g/m ² /24h or more provided on a surface opposite to the surface of the second adhesive layer in contact with the polarizer,
The first adhesive layer and the second adhesive layer are the polarizing film of the adhesive film according to claim 7. The method according to claim 11, a surface in contact with the polarizer of the first adhesive layer; and an adhesive strength of a surface of the second adhesive layer in contact with the polarizer of 200 gf/inch or more. The method of claim 11,
The first adhesive layer and the second adhesive layer are the same polarizing film. A display device comprising the polarizing film according to claim 11 .

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